Bending machine

ABSTRACT

A bending machine which bends tubes in both directions and which can form bends of different radii. A bending die assembly has two bending hubs, each with an axis of rotation, so that when the tube is to be bent in one direction the die unit turns about one axis and when the tube is to be bent in the other direction the die head turns about the other axis, the assembly being replaceable by another having bending hubs of a different radius to form bends of a corresponding radius in a tube.

United States Patent Clarke et al.

[54] BENDIN G MACHINE [72] Inventors: Kenneth W. Clarke, Arcadia; DonaldL.

Kinnsch, Los Alimitos; Archibald R. Mc- Clay, Costa Mesa, all of Calif.

Foster Wheeler Corporation, Livingston, NJ.

22 Filedz Mar. 13, 1970 [21] Appl.No.: 19,172

[73] Assignee:

[52] U. S.Cl ..72/157,72/306, 72/321 [51] Int. Cl t ..B2ld 7/04 [58]Field ofSearc h ..72/153,157,2l7,306,310,

[56] References Cited UNITED STATES PATENTS Kritzer, .lr ..72/306Armstrong et al. ..72/217 Payne ..72/217 [451 Apr. 25, 1972 2,033,4233/1936 Frank ..72/217 1,546,147 7/1925 Skinner..... ....72/217 1,624,8044/1927 Robinson ..72/157 2,474,276 6/1949 Payne ..72/153 PrimaryExaminer-Charles W. Lanham Assistant Examiner-Michael J. KeenanAttorney-John Maier, 111, Marvin A. Naigur and John E. Wilson 57ABSTRACT A bending machine which bends tubes in both directions andwhich can form bends of different radii. A bending die assembly has twobending hubs, each with an axis of rotation, so that when the tube is tobe bent in one direction the die unit turns about one axis and when thetube is to be bent in the other direction the die head turns about theother axis, the assembly being replaceable by another having bendinghubs of a different radius to form bends of a corresponding radius in atube.

7 Claims, 7 Drawing Figures PATENTEU APR 2 5 1972 SHEET 10F 3 IINVljNlURS KENNETH W. CLARKE DONALD L.IUNNSCH ARCH/BALD R. MCCLAY ATTORNE Y PATENTEUAPR 2 5 m2 sum 3 UF 3 INVENTORS.

KENNETH W. CLARKE DONALD L. KINNSCH ARCHIBALD R. McCLAY we. W

AT TORNE Y 1 BENDING MACHINE BACKGROUND OF THE INVENTION There are manyinstances in industry where tubing must be bent in several directionsover its length. An example is found in the boiler making industry wherewater tubes must be bent into a serpentine configuration to be used ascomponents in the panels which are placed in the furnace area to conveywater into the furnace area and to carryout the steam which is formed inthem. Economizers and superheaters are also usually formed by bendingtubes into serpentine configurations. In these cases, it is alsonecessary to bend each tube in both directions several times over itslength.

In the past, equipment has been designed to carry out such bendingoperations but it has been somewhat inflexible in that it has only beenable to form tube configurations having bends of one given radius. Inthe manufacture of furnace panels, economizers, superheaters and othercomponents for boilers, different boilers will require different sizedcomponents so that it is desirable to have an apparatus which can beused to bend tubes so that the final configuration can have bends with aradius suitable for the boiler in which the component will be used.Undoubtedly, there are many other applications in industry where tubes,especially heavy tubes, must be bent in both directions to form apredetermined serpentine configuration, and where it is desirable thatapparatus be available to provide for the manufacture of suchconfigurations having different radii of bend.

SUMMARY It is the object of the present invention to overcome drawbacksfound in the prior art, such as those set forth above. Accordingly, thepresent invention provides a bending machine having an interchangeablebending die assembly with two bending surfaces, each of which has itsown axis about which the assembly may be rotated to bend the tube in aparticular direction, the radius of bends formed in the tube beingchangeable by using die assemblies having different distances betweenthe two axes and bending surfaces of different radii of curvature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side viewpartly in section showing a bending machine according to the preferredembodiment of the present invention;

FIG. 2 is a fragmentary plan view of the bending machine of FIG. 1;

FIG. 3 is a front view partly in section of the bending die assemblyshown in FIGS. 1 and 2 but in an enlarged scale;

FIG. 4 is a plan view of the lower die of the die assembly shown in FIG.3;

FIG. 5 is a fragmentary plan view with parts broken away showing aportion of the machine shown in FIG. 1;

FIG. 6 is a front elevation of the same; and

FIG. 7 is a front view partly in section showing die heads for forming atube configuration having radii of bend different from one formed by thedie heads shown in FIGS. 1, 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A bending machine 10which is shown in FIG. 1 has a frame 12 with a U-shaped section 14 openat the front end thereof and with a rear leg 16 and two forwardlyprojecting legs 18 and 20. The lowermost leg 20 has secured to it adownwardly projecting bracket 22 which supports two parallel hydrauliccylinders 24 and 26. The cylinders 24 and 26 rotate a plurality ofsprockets 30 which are secured for rotation about a common shaft 32 byoperating on the opposite sides of a pinion gear through racks which aresecured to each of the piston rods of the cylinders. The pinion issecured to the lower end of the shaft 32 to which the sprockets 16 aresecured. The pinion and rack arrangement is more or less conventionaland therefore not shown in detail.

The shaft 32 is split into a lower portion and an upper portion whichare separated by a clutch mechanism 34, which has an upper disc 36secured to the bottom of the upper portion of the shaft 32 and a lowerdisc 38 secured to the lower portion thereof, each of the discs 36 and38 having a longitudinally ex tending slot in which a key 40 can fitwhen the slots are vertically aligned. The key is always connected withthe upper disc 36 and can be pushed into the slot in the lower disc 38to lock the discs 36 and 38 together by means of a hydraulic cylinder 42which operates when the slot in the disc 38 is in the vicinity of thatcylinder. The key is removed by a hydraulic cylinder 44 which acts on ahorizontally extending rod (not shown) which moves the key 40 to theright and out of engagement with the slot. The clutch mechanism 34permits the cylinders 24 and 26 to rotate the upper portion of the shaft32 as many rotations in one direction as desired. If it were: not forthe clutching mechanism 34, the hydraulic cylinders 24 and 26 couldrotate the shaft 32 only until they reach the end of their stroke oruntil their respective rack gears no longer had teeth in mesh with thepinion.

As pointed out above, the plurality of sprockets 30 is mounted on theupper portion of the split shaft 32. Each of the sprockets 30 mesheswith a chain 44, which in turn meshes with one of a plurality ofsprockets 46 secured on a vertical shaft 48 which extends parallel tothe shaft 32. The shaft 48 passes through bearings which are mounted ina vertical member 50 of the frame 12.

Mounted on the upper end of the shaft 48 is a support block 52, whichwhen the shaft 48 is rotatedl by the hydraulic cylinders 24 and 26through the chains 44 and sprockets 30 and 46, will rotate with theshaft 48. In the upper surface of the support block 52 is a groove 58,and engaged within the groove 58 is a slide block 60 which forms thebase of a bending die assembly 62.

The bending die assembly 62 as shown in FIGS. 1 and 3 has an upper dieblock 64 and a lower die block 66. The lower die block 66, which isshown by itself in FIG. 4, has a left bending hub 68 and a right bendinghub 70, each bending hub being surrounded over most of its circumferenceby a groove. Thus, the left bending hub 68 has a groove 72 which opensupwardly and outwardly. The groove 72 extends from the rear portion ofthe hub about the axis of the hub to a straight hole 74, which extendsbetween the bending hubs 68 and 70 from the rear of the lower die block66 to the front thereof. In a like manner, the right bending hub 70 has.an upwardly and outwardly opening groove 76, which is symmetrical withrespect to the groove 72 so that both grooves are joined in the straighthole 74.

The upper die 64 has a left bending hub which is surrounded over most ofits circumference by a downwardly and outwardly opening groove 82 and aright bending hub 84 with a downwardly opening groove 86. The groove 82overlies the groove 72 over their respective lengths while the groove 86overlies the groove 76 over their respective lengths. In this manner,the grooves 72, 76, 82 and 86 define the straight hole 74 over theirco-extensive straight portions.

Extending through the left bending hub 80 of the upper die block 64 is abore 90 which is aligned with a bore 92 in the left bending hub 68 ofthe lower die block 66. Similarly, the right bending hub 84 of the upperdie block 64 has a bore 94 which is in alignment with a bore 96extending through the right bending hub70 of the lower die 66.

The aligned bores 90 and 92 are coaxial with the axis about which thebending die assembly 62 rotates when a tube is bent about the leftbending hub 68. Similarly, the aligned bores 94 and 96 are co-axial withthe axis about which the bending die assembly 62 rotates when the tubeis bent about the right bending hub.

In order to position the tube for each bend, it is pushed through thehole 74 until the location at which a bend is to be formed is reached.At that point the advancing tube is stopped and the bending die assembly62 is rotated, the direction of rotation depending upon the directionthe tube is to be bent.

The distance the tube is moved through the hole 74 will, of course,depend upon the distance between adjacent bends in the finishedserpentine configuration. The distance will probably not be the samebetween the various bends, so that preferably the present invention isprovided with a means of programming into it the distance between thebends and the degree to which the tube is to be bent at each bendlocation. It is desirable that the operation also be programmed so thatno weld in the tube is present at or near the location where the bend isformed.

To form a bend with smoother sidewalls by eliminating ripples, apressure wiper die 100 is provided. The pressure wiper die 100 has twodie halves 102 and 104 between which the tube extends and which movetoward each other to apply pressure when the bend is being formed andaway from each other to release the tube to permit it to pass throughthe pressure wiper die. As shown best, perhaps, in FIG. 6, the die half102 is provided with a groove 106 running along its length which faces agroove 108 in the die half 104. The tube passes through the wiper die100 so that it is always within the grooves 106 and 108. The pressurewiper die halves 102 and 104 are moved relatively to one another byhydraulic cylinders. They each are activated in the same manner andtherefore only one is shown in detail in FIG. 6. A hydraulic cylinder110 moves the die half 102 into position through an eccentric 112 whichacts on a sliding die cradle 114. When the die half 102 has been movedso that it is as close to the die half 104 as possible, pressure isexerted by means of a hydraulic cylinder 120 which acts through aneccentric 122 to apply a force to an arm 124 in the sliding die cradle114.

The die half 102 has a nose portion 126 which is curved in plan and thedie half 104 has a nose portion 128 which is curved in plan. The noseportions 126 and 128 are on the for ward end of the die halves 102 and104 respectively, as shown in FIG. 5, and are positioned between thebending hubs 68 and 70 in engagement with the hubs when the bending dieassembly 62 is in a neutral position, i.e., a position when it exerts notorque on a tube extending through the hole 74.

It has already been explained that torque is applied to the tube byrotating the bending die assembly 62 about one of the axes of thebending hubs 68 or 70. In order to allow a tube to move through thestraight hole 74 when the tube is being positioned'for asubsequentbending operation, and in order to permit the grooves 72, 82,76 and 86 to bear against the tube over half of its outer surface whenbeing bent, it is necessary to provide means to move the upper die block64 and the lower die block 66 with respect to one another.

The upper die block 64 is raised and lowered with respect to the lowerblock 66 by means of a hydraulic cylinder 130 (FIG. 3) which actsthrough a rod 132 secured to the upper die block 64. The hydrauliccylinder 130 never moves in relation to the lower block 66 because it isapaced therefrom by supporting columns 134 and 136. The column 134extends through the bores 90 and 92 and is secured to the lower dieblock 66 and slide block 60 by screw threads as shown. The column 134,however, is not snugly engaged within the bore 90 so that the upper dieblock 64 is not prevented from moving vertically by the column 134.Similarly, the column 136, which extends loosely through the bore 94,extends into the bore 96, is threadably engaged therein, and is securedto the slide block 60. The bending die assembly 62 including the lowerdie block 66 and the upper die block 64 is raised and lowered by meansof a hydraulic cylinder 140 (FIG. 1) which acts on the shaft 48, supportblock 52 and slide block 60 to raise and lower the die assembly 62. Toseparate the upper die block 64 and lower die block 66, the cylinder 140lowers the entire die assembly 62 while the cylinder 130 raises theupper die block 64. To position the upper and lower blocks together, thecylinder 140 raises the die block assembly 62 while the cylinder 130lowers the upper die block 64.

When the tube has been positioned in preparation for the formation of abend and the pressure wiper die 100 has been activated so that the diehalves 102 and 104 exert pressure on the tube, the upper die block 64and the lower die block 66 of the bending die assembly 62 are movedtogether. Thereafter, the bending tube assembly 62 is rotated about oneof the axes of the bending hubs 68 or 70.

In order to allow the bending die assembly to rotate selectively aboutone of two different axes, the shaft 48 is moved laterally with respectto the bending die assembly. When this happens the support block 52moves in relation to the die assembly 62 because the slide block 60remains stationary. To this end, the bending die assembly 62 is providedwith two bearings 144 and 146, each positioned co-axially with an axisof one of the bending hubs 68 or 70. Thus, as shown in FIG. 3, thebearing 144 is axially aligned with the axis of the left bending hub 68while the bearing 146 is axially aligned with the axis of the rightbending hub 70. If it is desired to bend the pipe to the left, i.e.,about the left bending hub 68, the shaft 48 is translated by means of ahydraulic cylinder 148 (FIG. 2) until the shaft 48 is aligned with thebearing 144. (The cylinder 148 actually moves the entire frame 12 sothat the shaft 32, clutch 34 and hydraulic cylinders 24 and 26 move withit.) At this point, a hydraulic cylinder 152 (FIG. 1) acts on a rod 154which extends axially through the shaft 48 to push a pivot pin 156upwardly and into engagement with the bearing 144. When the pivot pin156 is in the bearing 144, a locking pin 158 is moved under it by acylinder 160. The hydraulic cylinders 24 and 26 rotate the shaft 32 andthe sprockets 30, the sprockets 46 through the chain 44, and thus theshaft 48 is made to turn. Rotation of the shaft 48 imparts rotation tothe support block 52 and the slide block 60. The slide block 60 is ofcourse a component of the bearing die assembly 62 which will rotateabout the axis of the shaft 48, which is also the axis of the pin 156and the left bending hub 68. When the bend is completed, the upper dieblock 64 and lower die block 66 are moved apart, as are the die halves102 and 104 of the pressure wiper die 100. The bending die assembly 62is rotated to its neutral position and the tube is advanced through thepressure wiper die and the bending die assembly 62 until a location ofthe tube in which a bend is to be made is positioned in the bending dieassembly 62. If a left hand bend is to be made, the pressure wiper diehalves 102 and 104 are moved together and made to exert pressure on thetube. Similarly, the lower die 66 and upper die block 64 are movedcloser together and the bending die assembly is rotated to the left ashereintofore described. If a right hand bend is to be made, the shaft 48is translated until the pin 156 can be engaged within the bearing 146.The hydraulic cylinders 24 and 26 then rotate the shaft 48 to the rightto make the bend.

FIG. 7 shows a pair of die blocks having an upper die block 172 and alower die block 174. The upper die block 172 and lower die block 174 arebasically similar to the die blocks 64 and 66 having grooves 176, 178,and 182, which correspond to the grooves 72, 76, 82, and 86respectively. The grooves 176, 178, 180 and 182 all merge in straightsegments to form the straight hole 184 through which the tube is movedin preparation for bending. The die block 172 has bores 186 and 188which correspond to bores 90 and 94, while the die block 174 has bores190 and 192 which correspond to the bores 92 and 96 of the die block 66.

The basic difference between the die blocks 172 and 174 and the dieblocks 64 and 66 is that the die blocks 172 and 174 are larger. Thedistance R controls the radius of bend in the tube so that the dieblocks shown in FIG. 7 will create a larger bend radius than the dieblocks shown in FIG. 3. If larger die blocks such as 172 and 174 areused, a slide block larger than the slide block 60 must be used so thatthe bearings will be farther apart than the bearings 144 and 146. Thisis necessary so that the axes of rotation will be the proper distanceapart to allow for a larger bend radius. If the bores 186 and 190 arealigned with a bearing in the support block and the bores 188 and 192are aligned with such a bearing, the distance S will correspond to thedistance between bearings. This distance will, of course, be larger thanin the case where smaller die blocks are used and the pin 156 will movea greater distance when moving between bearings to change the axis ofrotation of the die assembly. This is possible because the slide blockcan slide in the supportblock 52 any distance which is necessary toassure engagement between the pin 156 and the bearing which will formthe axis of rotation.

' The foregoing describes but one preferred embodiment and otherembodiments can be constructed by making additions, subtractions and/orsubstitutions of elements in the abovedescribed embodiment withoutexceeding the scope of the invention as defined in the following claims.

What is claimed is:

1. Apparatus for bending a tube comprising a die assembly having acentral opening for receiving said tube, two bending surfaces, one oneach side of said opening, and two axes of rotation, one on either sideof said tube, two bearings in said die assembly, each of said bearingsbeing concentric with one of said axes of rotation, a pin which iscapable of being in serted in the bearing concentric with the axis ofsaid bending die assembly about which said bending dieassembly is to berotated to bend said tube, the other of said bearings being free toallow said die assembly to rotate about said engaged bearing, and meansto rotate said die assembly about either of said axes in eitherdirection whereby when it is desired to bend said tube toward one ofsaid axes, said assembly is rotated about that axis so that the tube isbent about the bending surface on the same side of said tube as said oneaxis.

2. The apparatus defined in claim 1 wherein said pin is mounted in asupport block for axial movement therein, said apparatus furthercomprising a slide block connected to said bending die assembly, saidbearings being in said support block, one of said slide blocks and saidsupport block having a groove in a surface thereof, the other of saidsupport blocks and said slide block being slideably engaged in saidgroove so that said slide block and said support block can be slid withrespect to one another so that said pin can be engaged in either of saidbearings, said means to rotate said die assembly acting on said slideblock.

3. The apparatus defined in claim 2 wherein said support block ismoveable to position said pin in either of said bearings.

4. The apparatus defined in claim 3 wherein said groove is in saidsupport block and a portion of said support block is slideably engagedin said groove.

5. The apparatus defined in claim 1 wherein said die as sembly comprisesan upper die block and a lower die block, means to hold said die blocksfrom relative horizontal move ment while permitting relative verticalmovement, means to move said die blocks apart to permit said tube to beadvanced through said die assembly and means to push said die blockstogether to hold said tube during bending.

6. The apparatus defined in claim 1 further comprising a pressure wiperdie, said die being positioned so that when said tube is advancedthrough said bending die assembly said tube passes first through saidpressure wiper die, said pressure wiper die comprising laterallydisposed die halves, said die halves each having a groove facing acorresponding groove in the other die half, means to move said diehalves together and against said tube to clamp said tube in said groovesand means to move said die halves apart to release said tube.

7. The apparatus defined in claim 6 wherein each of said die halves hasa curved nose portion complimenting and in engagement with the adjacentbending surface on said bending die assembly when said axes of rotationlay on a line perpendicular to said tube so that when said bending dieis rotated about one of said axes of rotation the curved nose portionclosest to that axis stays in contact with the bending surface closestto that axis.

1. Apparatus for bending a tube comprising a die assembly having acentral opening for receiving said tube, two bending surfaces, one oneach side of said opening, and two axes of rotation, one on either sideof said tube, two bearings in said die assembly, each of said bearingsbeing concentric with one of said axes of rotation, a pin which iscapable of being inserted in the bearing concentric with the axis ofsaid bending die assembly about which said bending die assembly is to berotated to bend said tube, the other of said bearings being free toallow said die assembly to rotate about said engaged bearing, and meansto rotate said die assembly about either of said axes in eitherdirection whereby when it is desired to bend said tube toward one ofsaid axes, said assembly is rotated about that axis so that the tube isbent about the bending surface on the same side of said tube as said oneaxis.
 2. The apparatus defined in claim 1 wherein said pin is mounted ina support block for axial movement therein, said apparatus furthercomprising a slide block connected to said bending die assembly, saidbearings being in said support block, one of said slide blocks and saidsupport block having a groove in a surface thereof, the other of saidsupport blocks and said slide block being slideably engaged in saidgroove so that said slide block and said support block can be slid withrespect to one another so that said pin can be engaged in Either of saidbearings, said means to rotate said die assembly acting on said slideblock.
 3. The apparatus defined in claim 2 wherein said support block ismoveable to position said pin in either of said bearings.
 4. Theapparatus defined in claim 3 wherein said groove is in said supportblock and a portion of said support block is slideably engaged in saidgroove.
 5. The apparatus defined in claim 1 wherein said die assemblycomprises an upper die block and a lower die block, means to hold saiddie blocks from relative horizontal movement while permitting relativevertical movement, means to move said die blocks apart to permit saidtube to be advanced through said die assembly and means to push said dieblocks together to hold said tube during bending.
 6. The apparatusdefined in claim 1 further comprising a pressure wiper die, said diebeing positioned so that when said tube is advanced through said bendingdie assembly said tube passes first through said pressure wiper die,said pressure wiper die comprising laterally disposed die halves, saiddie halves each having a groove facing a corresponding groove in theother die half, means to move said die halves together and against saidtube to clamp said tube in said grooves and means to move said diehalves apart to release said tube.
 7. The apparatus defined in claim 6wherein each of said die halves has a curved nose portion complimentingand in engagement with the adjacent bending surface on said bending dieassembly when said axes of rotation lay on a line perpendicular to saidtube so that when said bending die is rotated about one of said axes ofrotation the curved nose portion closest to that axis stays in contactwith the bending surface closest to that axis.